I'd give you my discord, for easier communication and idea sharing, but haven't find PM function here...
But if I get something in mind - I'll be glad to share ^^
For TFs, I've seen cow, sheep, cat in the files that waiting for nex updates. Maybe add something like sergals, dryad, Chinese dragon, horse or even some sort of living pool toy. But probably most of them you already planned ^^`
With artifacts will be fun to add some that umplify or change specie related abilities (like evolution, but artifacts) also will be nice to get specie scroll from the shop, after you open few of them.
Also have some ideas for hiden achievements, but don't think it's good to tell about them where someone can get a spoiler ^^`